audio/micrecord/source/micrecord.c

#include <nds.h>
#include <stdio.h>

//the record sample rate
#define sample_rate  8000

//buffer to hold sound data for playback
u16* sound_buffer = 0;

//buffer which is written to by the arm7
u16* mic_buffer = 0;

//the length of the current data
u32 data_length = 0;

//enough hold 5 seconds of 16bit audio
u32 sound_buffer_size = sample_rate * 2 * 5;

//the mic buffer sent to the arm7 is a double buffer
//every time it is half full the arm7 signals us so we can read the
//data.  I want the buffer to swap about once per frame so i chose a
//buffer size large enough to hold two frames of 16bit mic data
u32 mic_buffer_size = sample_rate * 2 / 30;


//mic stream handler
void micHandler(void* data, int length)
{
    if(!sound_buffer || data_length > sound_buffer_size) return;
    
    
    DC_InvalidateRange(data, length);

    dmaCopy(data, ((u8*)sound_buffer) + data_length, length);
    
    data_length += length;

    iprintf(".");
    
}

void record(void)
{
    data_length = 0;
    soundMicRecord(mic_buffer, mic_buffer_size, MicFormat_12Bit, sample_rate, micHandler);
}

void play(void)
{
    soundMicOff();
    soundEnable();
    iprintf("data length: %i\n", data_length);
    soundPlaySample(sound_buffer, SoundFormat_16Bit, data_length, sample_rate, 127, 64, false, 0);
}

int main(void) 
{
    int key;
    bool recording = false;

    sound_buffer = (u16*)malloc(sound_buffer_size);
    mic_buffer = (u16*)malloc(mic_buffer_size);

    consoleDemoInit();

    iprintf("Press A to record / play\n");

    while(1) 
    {

        scanKeys();
        key = keysDown();

        if(key & KEY_A)
        {
            recording ? play() : record();
            recording = !recording;
            iprintf("%s\n", recording ? "recording" : "playing");
        }

        swiWaitForVBlank();

    }
}